The 770's connected directly to a USB port on the Mac, not through a hub or anything? (It should be connected directly) The 770 hasn't booted completely and the MMC card mounted on the Mac? (It should be sat with a screen showing nothing but the USB icon IIRC) What version of Mac OS X do you have? (I'd say it should be 10.3 or above, but haven't tested on anything below 10.3) You've got a PPC Mac, not an Intel one? (flasher-2.0.macosx is a PPC binary, not sure how well it'll work under Rosetta) What happens if you run it as root? Andrew